The present invention relates to a spray boom assembly and control system therefor and, more particularly, to such boom assembly and control system for use with spray booms which are vehicle mounted.
Spray boom assemblies have been employed in the past which have been mounted for transport on tank vehicle for the spreading of liquids along a substantially wide path in the direction of movement of the vehicle. Such spray boom assemblies are frequently capable of being moved between a rigged in position for transport and a rigged out or extended position for spraying operation.
An example of such vehicle mounted spray boom assembly is shown in one of the present co-inventors U.S. Pat. No. 3,887,132. As disclosed in that Letters Patent, a single hydraulic cylinder may be employed for rigging in and rigging out the spray boom and also for elevating the spray boom as desired upon rig in. A shock absorber cylinder is also shown in said Letters Patent extending between the movable and fixed portions of the spray boom assemblies to dampen shocks due to vertical movement of the spray boom when the boom has been rigged out and the vehicle is moving.
The present invention is a substantial improvement in the spray boom assembly disclosed in said Letters Patent.
In one improved feature of the present invention, a breakaway construction prevents accidental damage to the rigged out booms in the event that collision occurs between a boom and a fixed obstacle, e.g. fence post, stump or the earth in a terraced field. In the present invention, not only is the boom capable of giving or breaking away to prevent damage to the boom, but the boom is automatically returned after the obstacle has cleared and the shock imparted to the boom assembly upon return is simply, inexpensively and rapidly dissipated.
In another improved feature of the present invention, additional means for tilting the boom upwardly once it has been rigged out enables operation of the boom assembly on terraced terrain without the tip of the boom assembly striking a higher elevation portion of the terrain as the vehicle moves. Such additional tilting is easily and inexpensively accomplished in the present invention without further manual action by the operator following rigging out of the boom.
In still another improved feature of the present invention along with the aforementioned features a pressurized fluid circuit and check valve assembly which is capable of substantially more sensitive damping of vertical movements of the booms during operation is provided.
In one principal aspect of the present invention, a spray boom assembly which is mountable on a vehicle for movement with the vehicle includes a boom and shock absorbing means for absorbing shock imparted to the boom assembly in a direction substantially parallel to the direction of movement of the vehicle, the shock absorbing means lifting the boom in a direction substantially perpendicular to the direction of the shock in response to the occurrence of the shock to dissipate the shock.
In still another aspect of the present invention, the shock absorbing means as previously set forth includes a first piston means coupled to the boom and operative to move a boom of the assembly in a plane substantially parallel to the direction of movement of the vehicle. Second piston means is also coupled to the boom and is operative to move the boom in a direction substantially perpendicular to the last mentioned plane. Fluid circuit means communicates these piston means. The first piston means moves in response to the shock imparted to the boom assembly to force liquid through the circuit means to the second piston means to move the boom upwardly to dissipate the shock.
In still another aspect of the present invention, the boom assembly includes hinge means to allow at least a portion of the boom to rotate from a first normal position, in which a portion of the boom extends substantially perpendicular to the direction of movement of the vehicle, to a second breakaway position in which the boom extends rearward of the vehicle upon striking an obstacle. Return means returns the boom portion of the first normal position when the boom portion has cleared the obstacle. Shock absorbing means absorbs the shock imparted to the boom assembly when the boom portion is returning to the first normal position by tilting the boom.
In still another aspect of the present invention, piston means and fluid circuit means are provided for absorbing shock due to movement of a boom in a direction perpendicular to the direction of movement of the vehicle. The latter fluid circuit means includes pressurizing means for maintaining the fluid in the circuit means at a pressure in excess of atmospheric pressure and check means provides substantially unrestricted flow of the pressurized fluid from the piston means upon upward movement of the boom and restricted flow of fluid from the piston means upon downward movement of the boom.
In still another aspect of the present invention, a boom assembly control system for moving a vehicle mounted boom between a rigged in and a rigged out position and for tilting the boom when it is in the rigged out position, includes first piston means for moving the boom between the rigged out and rigged in positions, second piston means for tilting the boom, a source of pressurized fluid, and control valve means for communicating the presurized fluid with the first and second piston means. The improvement in such control system includes at least one movable port in the control valve means and circuit means which communicates the port with both the first and second piston means and each of these piston means with each other to cause the first piston means to swing the boom from the rigged in to the rigged out position and the second piston means to tilt the boom without further movement of the control valve means port when the first piston means has fully rigged out the boom.
These and other objects, features and advantages of the present invention will become clear upon consideration of the following detailed description.